1. Field of the Invention
This invention relates to a slitter for slitting a wide web into narrow strips, and more particularly to a slitting width changing system for changing the slitting width (or the widths of the strips slit from the wide web) in such a slitter.
2. Description of the Prior Art
In a slitter for slitting a wide web into narrow strips, generally, the wide web is fed in the longitudinal direction thereof and is slit by a slitting blade or slitting blades mounted on a shaft which extends in the transverse direction of the wide web. Conventionally, change of the slitting width has been manually performed. Recently, there has been proposed a slitting width changing system for automatically changing the slitting width in such a slitter as disclosed, for instance, in Japanese Patent Publication No. 62(1987)50276 and Japanese Unexamined Patent Publication No. 63(1988)-134193.
In any one of the slitting width changing system disclosed in the patent publications, each slitting blade is held by a slitting blade holder which is mounted on the shaft so that it can be locked on and released from the shaft, and the slitting width is changed by releasing the slitting blade holder from the shaft, shifting it along the shaft and then locking it again on the shaft. However, since in the slitting width changing system, locking and releasing of the slitting blade holder are effected by rotating the shaft, it is very difficult to control the locking torque. When the locking torque is excessively large, the outer surface of the shaft can be scratched, which can prevent the slitting blade holder from being shifted along the shaft. On the other hand, when the locking torque is too small, the slitting blade holder cannot be firmly held in place.